Cross the threshold of the smallish Texas limestone building that serves as mystery writer David Lindsey's personal library and work space, and you find yourself in a room with narrow windows tucked under the eaves of a high ceiling. Sunlight drifts down over comfortable chairs and sofas, two desks made of dark polished wood, well-worn rugs, and books. Walls of books. From left to right door-jamb, baseboard almost to the ceiling, books. More than four thousand of them, to be exact.

Four thousand books should qualify as a collection, and Lindsey himself describes the library that way. To me it seems somehow less like a collection-a word that evokes signed rarities kept behind glass-and more like an extremely large hybrid personal library and working reference resource. The library itself is almost as orderly as a university reading room, minus, of course, the drowsy students and scratching pens. But here and there are touches of the personal: a few piles of papers on the corner of a polished wooden desk, a collection of inkwells near the door, a haphazard stack of books and magazines leaning against the legs of the coffee table that occupies the space between Lindsey and myself.

Feeling rather haphazard myself, I sit on a couch in Lindsey's personal library, trying to remember how my new MP3 recorder works. If you fumble with a funny-looking piece of electronics long enough, someone is sure to ask you just what it is you are fumbling with. Which Lindsey does, seeming inordinately interested, wanting to know what it is, how it works, where I got it. It's a treatment I suspect he may give anything unfamiliar, an approach that combines the thoroughness of a vacuum cleaner with the scientific method.

To distract him, I ask him about his collection: "What kinds of books do you have here?"

"Let's see…Oh, lots of stuff." He casually ticks off a few categories, gesturing toward various parts of the room. "Forensics, criminology-I use those a lot of course. Some anatomy. I use that in my work too. Architecture, ancient history. There's some religion over here, also some philosophy. Over here, I keep copies of all my books." He points toward a comparatively narrow section of shelves supporting pristine-looking, colorful paperbacks and glossy-jacketed hardback novels.

Forensics, criminology and anatomy, I think as I program my little recorder, combined with religion and philosophy make a good starter recipe for David Lindsey's writing. A creator of consistently successful mystery novels, several featuring his series character Stuart Haydon, he occupies his genre comfortably, and has built an equally comfortable living from it. At the same time, he's stretched the genre to fit an expansive, roving, intelligent sensibility, one that infuses his intricately turned plots with a challenging, double-edged sense of good and evil. In a David Lindsey novel, the tension comes not only from others, but also from within; his leading characters face danger not only in the form of drug smugglers, rogue cops, and serial killers hiding in unexpected places, but also from their own inner darkness.

This sensibility runs underneath a sensual writing style, meticulous research, and sure knowledge of his public. The combination has made him both a successful writer and an acclaimed one. All but the earliest of his books enjoy steady sales both here and overseas; translations can be found in twenty languages, including German, French, Greek, and Japanese. In 1992, Body of Truth, a novel featuring Houston homicide detective Stuart Haydon, won Germany's Bochumer Krimi Archiv award for the best suspense novel of the year.

While it's true that David Lindsey is a student of the darker side of human nature, there's no hint of it in his appearance. He seems friendly, calm, and rational. A man in his late fifties, with a tidily trimmed salt-and-pepper goatee and wearing casual but neat clothes, he looks as composed as his surroundings. And why would he appear any other way? Though he writes with skill and flair, David Lindsey is no tortured artist; in many ways he strikes me simply as a workaday man with a job he loves, one that happens to support him and his wife of twenty years, Joyce Lindsey, more than passably well. It's easy to see that this library was built in part by the glossy hardbacks and stiff-spined paperbacks occupying the nearby narrow shelf.

Lindsey grew up in West Texas and attended college at North Texas State University, earning a bachelor's degree in European literature. He spent a year in graduate school and nine years in publishing-at one point owning and operating his own small publishing company, Heidelberg Press. Drawn to other people's books, he nursed a passionate desire to write. But with two young children, he resisted the idea as "irresponsible."

"I married young. We had children young. I had a lot of responsibilities that would be put at risk by beginning a writing career," he wrote in an e-mail after our interview. Though he had never written anything for publication-had never showed his work to anyone-"I knew in my gut that I could write, but it just seemed an irresponsible thing to begin doing with a young family." So he waited until he was thirty-five, when he couldn't stand it any longer. Out of concern for financial security, he selected the mystery genre for its consistent marketability. "I conducted a little survey to see what kinds of books had sold well, consistently, over the decades. It turned out that the mystery genre filled that requirement," he writes. He bought about twenty mystery novels, selecting for a wide range of styles. After careful evaluation, he came to see the mystery genre was potentially huge, encompassing, as he says, "Dostoyevsky to Mickey Spillane."

Having found for himself a field of writing that he believed could be both profitable and creatively satisfying, he honed his skills over the next few years. After several false starts, he published his first two novels: Black Gold, Red Death, about a San Antonio newspaper reporter who becomes entangled in Mexican revolutionary politics, and A Cold Mind, featuring Stuart Haydon. Both books appeared the same year, in 1983. Black Gold became lost in the shuffle, but protagonist Stuart Haydon, an independently wealthy Houston cop, began to build a strong, steady following. Lindsey gained a reputation as a writer of dependably pleasing mystery thrillers with an often introspective flavor and a sometimes stunning flair for violence.

The clarity of Lindsey's writing about Houston was fueled in part by meticulous research and intensive experience. He had embarked on a career as a mystery writer yet he knew nothing about being a homicide detective. "This was in the early nineteen-eighties, when I was working this way," he says. "I'd go down to Houston probably two to three times a month, stay three or four days at a time. I did that for over a decade." During that time, Lindsey says, he absorbed all he could of the city and its police department. It was a dark, intense world, and it fascinated him. "I made good contacts in the department. I went on ride-alongs, visited crime scenes, witnessed autopsies. But I wasn't prepared for the violence that I saw during those early years of research.

"In those days the city morgue was in the old Ben Taub Hospital," he says. "I've seen that place when the morgue was full, the overflow spilled out into the halls, which would be lined with gurneys of bodies, the offices had gurneys of bodies. It was stunning. And, naturally, fascinating." These grisly experiences found their way into his writing in an unexpected way. Lindsey's time with the Houston Police Department taught him, he says, "how genuinely complex human life is."

In each book, Stuart Haydon, an improbably cultured and financially well-off detective, plied his trade on Houston's grimy city streets, wandering through a humid miasma of violence and treachery. The ironic combination had a powerful appeal. And Lindsey's ability to bring to each book a complex moral vision simply put more brawn on already strong bones.

For Lindsey, that moral vision illuminates a world painted in shades of gray. A running theme in his novels, even the most commercially oriented of them, is the complexity of humanity. Again and again, his characters are forced to face their own potential for evil or for complicity in evil. To save the lives of his family, for example, Titus Cain in 2003's The Rules of Silence has to enlist the help of a ruthless killer. "Even good people do shameful things," he says. "Those of us who are honest admit that. We're an amalgam of good and evil, and have been ever since the Garden."

"After a while, though, I suppose I got my fill" of Houston and the police department, Lindsey says. "I visited less frequently. It was wearing a little thin." There was a hermetic, closed-in quality to the Stuart Haydon novels, even when Lindsey's plots sent the detective to Mexico City, as it did for In the Lake of the Moon. "The Haydon books were all very internal. I really wanted to look outward."

He reached a watershed moment with Mercy, a highly successful book that brought him added prominence and, ironically, defined his work at a time when he wanted to change direction. "Mercy was an intense experience. It started as an accident, really. I was researching another Stuart Haydon novel. And I was on a ride-along with an FBI agent, riding around Houston. We started talking about Quantico (home of the FBI Academy, a premier learning and research center located in Virginia) about (serial killer) profiling, all of that. It just grabbed my interest." He switched from the Haydon novel and began researching and writing Mercy.

In his initial research, Lindsey had noticed that profiling focused on male serial killers almost exclusively. "I wondered what would happen if a woman did this. Would the profilers notice, would they pick up on it? Because the people I spoke to at Quantico-they were unanimous-they said, 'Women don't do that. Women don't commit sexual violence.' This was before Aileen Wuornos," he adds, referring to the Florida female serial killer executed in 2002. (Wuornos was the subject of the 2003 movie, Monster, which won Charlize Theron an Academy Award for portraying the killer.)

Mercy, a novel about a female detective hunting a seemingly androgynous serial killer who preys on a circle of bisexual upper-class Houston women, came out in 1990. It combined breathtaking violence with tantalizing sexuality and added a strong female protagonist in the person of Latina detective Carmen Palma. In short, it was a hit. "At that time," Lindsey says, "serial killer novels weren't common. Mercy started that whole trend. My book and another book, by Thomas Harris, Red Dragon, that started the whole thing.

"In popular fiction," he continues, sounding slightly exasperated, "if you have one big success, they say, 'We want you to do this again.'" But Lindsey felt burned out. The experience of researching and writing Mercy, of interviewing killers and abused women, of delving deeply into the psychology of the damaged, had been overwhelming. Much to the frustration of his agent and editors, he refused to write another novel about a serial killer. Even now he's firm in his decision: "There are certain things I don't want to think about anymore," he says simply.

Instead, he wanted to write about a longtime interest of his. "I had always been fascinated by intelligence (work)," he said. "But the thing I didn't know was how much people want the same thing. There really is this pressure to produce-they want 'more of the same, but different.' And that's simply numbing for a writer."

Stuart Haydon returned for one more book, Body of Truth, which took him to Guatemala. In Body of Truth, Haydon flies down to the strife-torn country in search of a missing young woman. The plot brings him in contact with rogue CIA agents, death squads, and corrupt politicians. The book was acclaimed critically and popularly. Reviewers compared it favorably to the work of novelist Graham Greene.

After Body of Truth, Lindsey shifted direction slightly, with 1994's An Absence of Light. Set in Houston but featuring Marcus Graver, a captain in the Houston Police Department's Intelligence Division, An Absence of Light traded explicit violence for a more subtle, brooding atmosphere of danger.

Having established that he could write a best-selling novel that didn't feature Haydon and wasn't necessarily an action-oriented mystery-thriller, Lindsey has continued to move away from his old stomping grounds. His last four novels, including The Face of the Assassin, which arrives in bookstores this month, have dabbled in a variety of genres, from international post-Cold War espionage to the novel of psychological suspense. Switching genres could be seen as a chancy step for a brand-name author of popular fiction. So far, however, the decision has not hurt him; the movie rights to his last novel, The Rules of Silence, were purchased in 2003 and the film is slated for production. It's an expansive time for the Austin author. But expansion in a time of media conglomerates and tightening bottom lines means a degree of constriction for authors of popular fiction.

Even as Lindsey carves out a new, wider space for himself, he says the pressures from publishers are changing the way he writes. Creatively, he says, the process is the same-that is to say, it's never the same. "It's different with every book. I start with a general idea, but what generates that idea is always different. It can be an image, or a question-it's always different. The only constant is that I don't outline."

Lindsey describes his writing process as amorphous and intuitive. "I find that the first hundred words are the most difficult. The hard part is never making up the story-it's all those initial choices that are hard," he says. I fleetingly imagine a not so composed David Lindsey perhaps pacing the floor of a not so orderly room, arguing with his characters in frustration or puzzlement. But he suggests that even if the creative process itself isn't changing, the writing is.

"Popular fiction is getting 'poppier,'" he says. "Writing is more attuned to short snappy paragraphs and dialogue. There are a zillion different ways to tell a story. And it's not that you can't tell a good story short, but the way we tell stories is changing." With the industrialization of publishing by large media conglomerates, fiction authors have become more vulnerable to market demands. "The rate of the demand," he says, "almost dictates the type of book you write." That demand, he says, is increasing, shortening the time between books and changing the books themselves. "It used to take two years to write a book," he says. "Now It's going to be every year, just to keep up." He expects that "my books will become shorter, probably. And some of the grace of language will probably go."

Bleak statements, especially for a man who will tell you that he views his writing as a calling and a gift. But give Lindsey a chance to talk about the international trade in counterfeit pharmaceuticals-the subject of an upcoming novel-and he leans forward, his eyes bright and focused, as he talks passionately and at length.

"It's a good subject," he said. "It's a sad thing. A friend of mine in the FBI told me these stories about people dying during surgery, because they received counterfeit drugs. It happens of course, because drugs are so expensive in the US-the prices are unregulated. So you have people buying medications over the Internet, which is just a huge risk. All over the world, drugs are being counterfeited rampantly. About twenty million packets of drugs enter the US from overseas each year, and none have been inspected. The drug cartels, organized crime, they're all into it. It's a rich, complex story," he concludes. The thought of delving into this complexity seems to cheer him up.

Ultimately, complexity is David Lindsey's element, which is perhaps a bit ironic, given that he has built his career on genres whose conventions themselves can be considerably less than nuanced. But despite pressure from others he's managed to stretch those genres enough to introduce a revivifying influence.

"Our president," he says with a touch of wryness, "is fond of talking about good and evil. I think we can oversimplify. We want to come up with short answers, simple answers. That's not how life is, and if we're honest, we'll admit that. I'm disappointed that we don't take more time to delve into deep things."

When she isn't profiling writers of mysteries, Barbara Strickland continues to work toward solving the her own mystery-that of the missing master's thesis. You may e-mail Barbara via editor@goodlifemag.com.

Novels by David Lindsey

The Face of the Assassin (2004)-Using the thinnest and scarcest of clues, forensic artist Paul Bern recreates the facial features of homicide or accident victims. His job takes a turn for the mysterious when a woman shows up at his door with a skull in a bag. She believes it's the remains of her husband, and she wants Bern to confirm her suspicion. It's only the first step down a shadowed, uncertain path strewn with spies, smugglers and international terrorists.

The Rules of Silence (2003)-Multimillionaire Titus Cain is approached with a strange proposition: if he doesn't give a certain man $64 million, this same man will kill off some (or perhaps all) of Cain's friends and loved ones. If Cain tries to seek help, the killings will start instantly. Cain is forced to rely on resources as shadowy-and possibly as dangerous-as his extortionist.

Animosity (2001)-Animosity is a subtle, chilling tale of obsession. Sculptor Ross Marteau accepts a commission from Celeste Lacan to sculpt her sister Leda, a preternaturally beautiful woman with a disturbingly malformed body. Marteau's involvement with both women draws him into their strange relationship. When someone close to them is killed, Marteau finds himself lost in a labyrinth of dark secrets and obsessions.

The Color of Night (1999)-A secret agent never really comes in from the cold. Former intelligence officer Harry Strand lives quietly as a widowed art dealer in Houston. After he discovers clues that his wife's death in an automobile collision was no accident, but revenge-and that the person responsible is hunting him as well-Strand's carefully constructed life begins to unravel. On the run, he is forced to fall back on old deceptions and treacherous alliances.

Requiem for a Glass Heart (1996)-As a skilled assassin for Russian crime boss Sergei Krupatin, Irina Ismaylova deceives her targets and kills them with ruthless efficiency. Cate Cuevas, Houston FBI agent, has been assigned to infiltrate Krupatin's trusted circle, with plans to arrest or kill him. Irina and Cate meet and bond, with only Cuevas knowing the truth about their situation, but neither one knowing whom to trust. Nothing is as it seems, and the initial plans quickly become a tense cat-and-mouse game.

An Absence of Light (1994)-Marcus Graver is captain of the Houston Police Department's Intelligence Division. When a cop in the division is found dead, Graver is brought in to determine whether it was suicide. Signs point to corruption both inside and outside HPD, and Graver recruits an elite undercover organization to help him track down the source-an ex-Mossad deep-cover agent turned world-class drug smuggler.

Body of Truth (1992)-In this, the most recent of the Stuart Haydon novels, the Houston homicide detective travels to Guatemala on a quest for a missing young woman, Lena Muller. Lindsey depicts Guatemala as a lethal place of death squads and double-dealing, where Lena appears to have revealed dirty political secrets, making her a target for execution. Haydon searches for the truth of Lena's disappearance, but finds only facts-facts that defy "truth." Lena becomes Haydon's grail, his elusive "body of truth."

Mercy (1990)-This book threw Lindsey into prominence and for a time defined his work. One of the first serial killer novels, Mercy features Houston detective Carmen Palma. Assigned to the case of a gruesome serial sex killer, Palma discovers a sort of sadomasochistic demimonde that includes some of the city's most prominent citizens. Exploring the psyches of a killer, and of those who willingly went to him or her, drives Palma to explore her own personal shadows.

In the Lake of the Moon (1988)-Houston detective Stuart Haydon receives five unfamiliar photographs: two of his late father, two of a strange woman in a Mexico City studio, and then, chillingly, a photo of Haydon himself, with a felt-tip-drawn bullet entering his head. Haydon's search for his stalker takes him to Mexico City, where he discovers a hidden chapter of his father's life and a disturbing obsession.

Spiral (1986)-Volatile international politics spill over the Mexican border and into Houston's streets. Stuart Haydon is assigned to investigate a series of grisly torture murders and finds himself drawn into a tangle of intrigue, greed, and corruption that involves a right-wing vigilante group known as Los Tecos.

Heat From Another Sun (1984)-Haydon's investigation of a motion-picture cameraman's brutal slaying sets him on the trail of a bizarre series of murders orchestrated for the cinematic pleasure of a wealthy, amoral man. Haydon's investigation eventually drives him to the edge of blackmail, betrayal, and murder, forcing him to contemplate his own capacity for evil.

A Cold Mind (1983)-A psychopath stalks expensive call girls, some of them from the upper echelons of Houston society. Stuart Haydon tracks a coldly efficient killer through the grimy streets of Houston to the renowned Texas Medical Center and into a harrowing confrontation.

Black Gold, Red Death (1983)-San Antonio newspaper reporter Martin Gallagher leads a quiet life. His sense of security is profoundly disturbed, however, when his half-sister Stella tells him she is the leader of a secret Mexican revolutionary movement. Stella begs Martin to smuggle some secret documents to a certain destination in Mexico. Wary but loyal, Martin agrees to help. He finds himself dodging informants, the FBI, the CIA, and a ruthless assassin known as Tony Sleep.

-Barbara Strickland, with material drawn from publisher's copy, Kirkus Reviews, Library Journal and Publishers Weekly.